Alkylation of aromatic hydrocarbons



Patente Dec. 1%, I

era

smmon or snom'rrc soc ns Universal Oil nets ilompany, Chicago,

a corporation of were Application May 31, 1941,

erlal No. scale:

20 Claims. (6i. zoo -s11) This invention relates to the treatment of aromatic hydrocarbons to produce alkylated are matic hydrocarbons. More specifically it is concerned with the production of mono-alkylated and poly-alkylated aromatic hydrocarbons in the presence of a catalyst.

It is recognized that in general the catalytic alkylationof aromatic hydrocarbons has been known for some time. However, the present invention difierentiates from the prior art on this subject in the use of a particular catalytic material comprising as its active ingredients. pyro= phosphate of a metal selected from members of the right-hand column of group I of the periodic table.

In one specific embodiment the present invention comprises a process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an oleflnic hydrocarbon to contact under alkylating conditions in the presence of a catalyst comprising as its active ingredient a pyrophosphate oi a metal selected from members of the right-hand column of group I of the periodic table, and preferably of copper-and silver.

Aromatic hydrocarbons, such as benzene, toluene, other almzlated benzenes, napththalene,

butadiene and isoprene, also carbons utilizable as alkylating agents are obtainable from any source and are present in products of thermal and catalytic cracking of oils, in those obtained by dehydrogenating paramnic and olefinic hydrocarbons or in the products resulting from dehydrating alcohols.

Alkylation of aromatic compounds may also be efiected in the presence of catalysts hereinafter described by charging with'the aromatic hydrocarbon a substance capable of producing olefinic hydrocarbons under the operating conditions chosen for the reaction. Such olefin-producing substances include alcohols, ethers, esters, and alkyl halides which are capable of undergoing olehydration or splitting to olefinic hydrocarbons, containing at least 2 carbon atoms per molecule, which may be considered as present in the reaction mixture even though possibly only as transient intermediate compounds which react further with aromatic hydrocarbons to produce alkylated naphthalenes, other poly=nuclear aromatics, etc., which are alkylated by olefl'nic hydrocarbons as hereinafter set forth, may be obtained by the distillation of coal, by the dehydrogenation of naphthenic hydrocarbons, by the dehydrogenation and cyclization of aliphatic hydrocarbons, alkylated aromatic hydrocarbons, and allrylated naphthenic hydrocarbons, and by other means.

Oleflnic hydrocarbons utilizable' as alkylating agents in the present instance comprise monoolefins and poly-oleflns. Oleflns which are employed in the present process are either noally gaseous or normally liquid and comprise ethylene and its higher homologs, both gaseous and liquid, the latter including various polymers of normally gaseous oleflns, but these difierent clefinic hydrocarbons and those mentioned hereinafter are not necessarilyequivalent in their action as alkyleting agents. Cyclic olefinsmay also serve in alkylating aromatic hydrocarbons but generally under conditions of operation different from those employed when alkylating aromatic hydrocarbons by non-cylic olefins, and this reaction may involve intermediate formation of oleflns from cycloparafiins in the presence of the catalyst. Other oleflnic hydrocarbons which may be interacted with the above indicated aromatic hydrocarbons include conjugated diolenns such as desired reaction products.

Catalysts suitable for use in effecting the process of the present invention comprise preferably copper and silverv salts of pyrophcsphoric acid as well as the materials formed by mildly treating these pyrophosphates at elevated temperatures with hydrocarbons, hydrogen, or other reducing gases prior to use as alhylating catalysts. The metal pyrophosphates utilized as alkylating catalysts may be formed by adding an aqueous solution of analltall metal pyrophosphate to an aqueous solution oi a water=soluble copper or silver salt to efiect precipitation of the desired metal pyrophosphate which may be separated by filtration from the precipitation mixture, then washed, dried, and formed into particles suitable for use as a reactor filling material.

Pyrophosphates of copper, "silver, or, mixtures thereof may be used as such or mixed with or deposited upon carriers or supporting materials such as silica, diatomaceous earth, alumina, magnesia,

silica-alumina composites, crushed porcelain,

pumice, firebrick, etc. A composite of a group I metal pyrophosphate, metal acid pyrophosphate, and 'a selected carrier in finely powdered form after thorough mechanical mixing, is subjected to dryin pelleting, and heating operations, the latter carried out in a stream of air, nitrogen, hydrogen, or hydrocarbon gases to produce formed particles of catalyst suitable for use as packing non-conjugated dioleflns, and other poly-oleflns. Oleilnic hydro- 3 formed into pellets or granules usually by compressing a mixture of the powdered metal pyrophosphate and a suitable pelleting lubricant such as hydrogenated cocoanut oil, starch, etc. The activity of supported metal pyrophosphate catalysts is also controlledto a substantial extent by varying the proportions of active metal pyrophosphate and carrier. Accordingly, catalytic material of appropriate activity is thus available for use with both substantially straight chain olefins and with the more reactive olefins such as those containing a tertiarycarbon atom as is present in isobutene, tri-methyl ethylene, etc..

The difierentalkylating catalysts which may thus be prepared and employed in the present process are not necessarily equivalent in their action.

In effecting reaction between aromatic hydrocarbons and an alkylating agent, as an olefinic hydrocarbon, according to the process of the pres- A simple procedure, utilizable in the case -for alkylating aromatic compounds with olefinic consists in contacting the aromatic and olefinic hydrocarbons with a catalyst containing a pyrophosphate of a metal selected from the members of the right-hand column of group I of the periodic table at a temperature of from about 100 to about 450 C. and preferably between about 250 and about 400 C. under a pressure of from substantially atmospheric to approximately 100- atmospheres. Intimate contact of the reacting components with the catalyst is effected bypassing the reaction mixture through a fixed bed of granular or pelleted catalyst or the reacting components may be mixed with finely divided catalyst and reacted in either a batch or continuous type of operation. The hydrocarbons subjected to reaction are preferably in the proportion of 1 molecular proportion of olefinic hydrocarbon to between about 2 and about 20 molecular proportions of aromatic hydrocarbon in order to diminish polymerization of olefinic hydrocarbons and to favor interaction of oleflnlchydrocarbons with the aromatic hydrocarbon or m'ixture of aro-- matic hydrocarbons in the hydrocarbon fraction,

undergoing treatment. The addition of a hydrogen-containing gas to the alkylation mixture frequently has a. beneficial effect upon the reaction.

'Thus a hydrocarbon mixture comprising essentially normally liquid aromatic hydrocarbons and a fraction containing olefinic hydrocarbons are commingled and passedthrough a reactor containing a pyrophosphate of copper and/or silver, or at least a portion of thearomatic hydrocarbon is charged to such a reactor while the fraction containing olefinic hydrocarbons, as such or preferably diluted by anotherportion of the aromatic hydrocarbon being treated, is introduced at various points between the inlet and the outlet of the reaction zone in such a way that the reaction mixture being contacted with the catalyst will at all 'times contain a relatively low proportion of the olefinic hydrocarbon and thus favor interaction of aromatic and olefinic hydrocarbons rather than polmerization of the latter.

While the method of passing the aromatic and olefinic hydrocarbons, either together-or countercurrently, through a suitable reactor containing the granular catalyst is generally customary procedure, the interaction of these hydrocarbons may also be effected in a closed vessel in which some of the reacting constituents arein liquid phase and in which the catalyst is preferably in finely divided form and is maintained in dispersion or suspension by some method of agitation, The choice of operating procedure is dependent upon the circumstances such as the temperature, pressure, and activity of catalyst found tobe most effective for producing the desired reaction between particular aromatic and olefinic hydrocarbons.

. Metal pyrophosphates as herein described are preferred catalysts as they permit continuous re-' action of aromatic and olefinichydrocarbons in the presence of a fixed bed of catalyst and thus make it possible to avoid mechanical problems as well as oxidation and corrosion diflloulties encountered when this reaction is carried out in I the presence of sulfuric acid which is sometimes used as an alkylating catalyst. Further, a, pyrophosphate of copper or silver also has the advantage over aluminum chloride utilized as catalyst hydrocarbons in that the metal pyrophosphate .forms substantially no addition compounds or complexes with aromatic and/or olefinic hydrocarbons while such formation of addition compounds 'is characteristic of catalysts containing aluminum chloride.

Reactions between aromatic and olefinic hy-,

drocarbons inthe presence of a pyrophosphate of a non-alkaline metal of group I of the periodic table are apparently of a relatively simple characteralthough they may be accompanied by certain amounts of polymerization and decomposition, the latter being particularly in evidence when the reaction is carried out at a temperature in the neighborhood of 450 C. While not understood completely, a typical alkylation of an arcmatic hydrocarbon by an olefin apparently involves the addition of the aromatic hydrocarbon to a double bond of an olefinic hydrocarbon'to produce a higher-boiling alkylated aromatic hydrocarbon which may in turn undergo further reaction with one or more molecular proportions of olefinic hydrocarbon to ,form' dialkylatedand tain limits it is possible to produce mainly mono-,

' alkylated aromatic hydrocarbons by proper adjustment of catalyst activity, ratio of the aromatic to the olefinic hydrocarbons charged, operating conditions such as temperature, pressure, and rate of feed of the reacting'components, etc.

The reaction between an aromatic hydrocarbon and a hexene or other normally liquid olefin of higher molecular weight may involve not only addition of aromatic and olefinic hydrocarbons but also a depolymerization or splitting of the olefinic hydrocarbon into olefinic fragments .of

lower molecular weights which react with the aromatic hydrocarbons to produce alkylated aro-' matic hydrocarbons. Thus benzene and di-isobutene or tri-isobutene react and yield tertiary butyl benzene and poly-tertiary butyl benzenes, while nonene and benzene yield both butyl and gara es amyl benzenes as well as other products by socalled depoly-alkylation. I

In general, the products formed by interaction of an olefinic hydrocarbon with a molal excess of an aromatic hydrocarbon are separated from the unreacted aromatic hydrocarbon by suitable means as by distillation, and the unreacted portion of the aromatic hydrocarbon originally charged and generally the poly-alkylated hydrocarbons formed are returned to the process and mixed with additional quantities of the ole= finic and aromatic hydrocarbons being charged to contact with the catalyst. This recycling of polyalkylated aromatic hydrocarbons sometimes aids in the production of mainly mono-alkylated aromatic hydrocarbons and depresses the forma= tion of more-highly alkylated derivatives. The total alkylated product thus freed from the excess of the orignally charged aromatic hydrocarbon is separated into desired fractions by distillation at ordinary or reduced pressure or by other suitable means. 1

While the process of this invention is particularly applicable to the production of alkylated aromatic hydrocarbons from aromatic and ole flnic hydrocarbons, it may be utilized also in alkylating other aromatic compounds as in converting phenols and olefinic hydrocarbons into alkylated phenols using a catalyst containing a pyrophosphate of a group I metal hereinabove set forth and generally operating within the ranges of temperature and pressure hereinabove set forth. The following examples are given to illustrate the character of results obtainable by the use of the present process, although the examples given are not introduced with the intention of unduly restricting the generally broad scope of the invention.

Emmple I A solution of 53 partsby weight (0.14 molecular proportions) of potassium pyrophosphate trihydrate in 600 parts by weight of water was added gradually with stirring over a period of 15 minutes to a second solution containing 63 parts by weight (0.25 molecular proportion). of copper sulfate pentahydrate dissolved in 1250 parts by weight of water. The precipitate so formed was washed by decantation three times using 1000 parts by weight of water in each wash. The precipitated material was then collected on a filter, washed again with 1000 parts by weight of water,

and afterward dried for 16 hours at 140 to 145 C.

Thus 38 parts by weight of light blue powdery copper pyrophosphate was obtained which represented 90% of the theoretical yield based upon the quantity of potassium pyrophosphate used in the precipitation.

The excess copper sulfate remaining in the mother liquor after precipitation of the copper pyrophosphate could be treated with more potassium pyrophosphate to produce an additional quantity of copper pyrophosphate.

parts by weight of the copper pyrophosphate prepared as hereinabove indicated, 80 parts by weight of benzene, and 20 parts by weight ofpro ,pene were charged to a steel autoclave which was then placed under 50 atmospheres initial nitrogen pressure and heated for 4 hours at 300 C. The resulting reaction mixture yielded 10 parts by weight of mono-isopropyl benzene and 2 parts by weight .of higher boiling, alkylated benzenes. A likereaction mixture after being heated for 4 hours at 350 C. was found to contain 35 parts by weight of mono-isopropyl benzene, and 5 parts by weight of more highly propylated benzenes.

Example II A solution consisting of 28 parts by weight (0.07

molecular proportion) of potassium pyrophosphate trihydrate dissolved in 600 parts by weight of water was added gradually with stirring over a period of minutes to a solution containing 45 v decantation three times using 1000 parts by weight of water in each wash after which the precipitate was collected on a filter and washed with 1000 parts by weight of water. The washed precipitate after drying for 16 hours at 140 C. yielded 37 parts by weight of yellowish brown granules of silver pyrophosphate thus equivalent to 93% of the'theoretical based upon the quantity of potassium pyrophosphate employed.

The excess silver nitrate remaining in the mother liquor after precipitation and separation of the silver pyrophosphate could be treated with more potassium pyrophosphate to produce an additional quantity of silver pyrophosphate.

10 parts by weight of the silver'pyrophosphate obtained as above described, 80 parts by weight of benzene, and 20 parts icy-weight of propane were charged to the rotating autoclave used in Example I, which was then placed under 50 atmospheres pressure ofnitrogen and heated 4 hours I at 300 C. After cooling the autoclave, the reaction product removed therefrom was found to contain 34 parts by weight of mono-lsopropyl benzene and 7 parts by weight of more highly propylated benzenes.

The nature of the present invention and its commercial utility can be seen from the specification and examples given, although neither section is intended to limit its generally broad scope.

I claim as my invention:

1. A process for producing aromatic compounds having a higher number or carbon atoms per molecule than the aromatic compound from which they are derived which comprises subjecting an aromatic compound and an o1efinic hydroearbon to contact under alkylating conditions in the presence of an alkylating catalyst whose alkylating components consist essentially of a pyrophosphate of a metal selected from the members of the right-hand column of group I of the periodic table.

2. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aro-' matic hydrocarbon and an olefinic hydrocarbon to contact under alkylating conditions in the presence of an allrylating catalyst whose alkylatlng components consist essentially of a pyrophosphate of a metal selected from the members of zhglrlght-hand column of group I of the periodic 3'. A; process for producing alkylated aromatic ydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact at a temperature of from about to about 450 C. in the presence of an alkylating catalyst whose alkylating components consist essentially 01 a pyrophosphate of a metal selected irom the members oithe right-hand column of group I of the periodic table. i

4. A process for producing alkylated aromatic hydrocarbons which comp e sub t g an aromatic hydrocarbon and an "olefinic hydrocarbon to contact at a temperature of irom about 100.

to about450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of an alkylating catalyst whose alkylating components consist essentially of a pyrophosphate of a metal selected from the members of the right-hand column of group I of the periodictable. I i 5. A process-for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and anolefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a hydrogen-containing gas and of an alkylating catalyst whose a1- kylating components consist essentially of a pyrophosphate of a metal selected from the members of the right-hand column of. group I or the periodic table.

6. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and a, normally gaseous olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure or from substantially atmospheric to approximately 100 atmospheres in the presence of an alkylating catalyst whose alkylating components consist essentially of a pyrophosphate of a metal selected from the members of the right-hand column of group I of the periodic table.

'7. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an ar matic hydrocarbon and a normally liquidolefinic hydrocarbon to contact at a temperature of from about 100 to about 450 from substantially atmospheric to approximately 100 atmospheres in the presence of an alkylating catalyst containing a pyrophosphate of a metal selected from the members of the right-hand column of group I of the periodic table.

8. A process. for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of an alkylating catalyst containing copper pyrophosphate.

9. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and an olefinic hydrocarbon to,

contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of an alkylating catalyst whose alkylatingcomponents consist essentially of silver pyrophosphate.

10. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an aromatic hydrocarbon and a normally gaseous oleflnic hydrocarbon to contact at a temperature of from about 110 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of an alkylating catalyst whose alkylating components consist essentially of copper pyrophosphate.

11. A process for producing alkylated aromatic hydrocarbons which comprises subjecting an arcmatic hydrocarbon and a normally liquid olefinic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of an alkylating C. under a pressure of catalyst whose alkylating' components consist essentially of copper pyrophosphate.

12. .A process for producing alkylated benzenes which comprises subjecting benzene and an oleflnic hydrocarbon to contact at a temperature of 13. Aprocess for producing alkylated benzenes.

' which comprises subjecting benzene and propene is to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of an alkylating catalyst consisting essentially of copper pyrophosphate.

14. A process for producing alkylated benzene which comprises subjecting benzene and propene to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of an alkylating catalyst consisting essentially of silver pyrophosphate.

15. A process for producing alkylated aromatic hydrocarbons which omprises subjecting an arcmatic hydrocarbon and an oleflnic hydrocarbon to contact at a temperature of from about 100 to about 450 C. under a pressure of from substantially atmospheric to approximately 100 atmospheres in the presence of a substantially inert carrier supporting an alkylating catalyst consisting essentially of a pyrophosphate of a metal selected from the members of the right hand column of group I of the periodic table.

16. An alkylation process which comprises reacting an aromatic compound with an olefin in the presence of an alkylating catalyst consisting essentially of a pyrophosphate of a metal from I$31551right-hand column of group I of the periodic characterized in that said catalyst is composited with a relatively inert supporting material.

18. An alkylation process which comprises reacting an aromatic compound with an olefin in the presence of a sulfuric acid-free alkylating catalyst comprising a pyrophosphate of a metal from the-right-hand column of group I of the periodic table.

19. A method for alkylating aromatic hydrocarbons which comprises contacting an aromatichydrocarbon with an olefin hydrocarbon at elevated temperature in the presence of catalytic material comprising as an essential ingredient copper pyrophosphate.

.20. A process for producing a mono-alkylated hydrocarbon which comprises alkylating an arcmatic hydrocarbon with an olefin in the presence carbons, and returning at least a portion of the poly-alkylated aromatic hydrocarbons to the alkylating step.

RAYMOND E. SCHAAD.

17. The process as defined in claim lfiiurther 

